Cover for crucible-furnaces.



J. L. R. BROWN.

COVER FOR GRUGIBLE FURNACES. APPLICATION FILED APR. 28, 1909 PatentedNov. 15, 1910.

' I INVENTOR WITNESSES: 12m 00% ATTORNEY JULIAN L. R. BROWN, OFBRIDGEPOR-T, CONNECTICUT.

COVER FOR CRUCIBLE-FURNACES.

Specification of Letters Patent.

Patented Nov. 15, 1910.

Application filed April 28, 1909. Serial No. 492,741.

To all whom it may concern:

Be it known that I, JULIAN L. R. BROWN, a citizen of the United States,residing at Bridgeport, county of Fairfield, State of Connecticut, haveinvented an Improvement in Covers for Crucible-Furnaces, of which thefollowing is a specification.

This invention relates to the class of furnaces which are especiallyadapted for melting metal in crucibles, and has for its object toprovide a cover for the furnace that will also serve as a cover for thecrucible and will prevent the flame from coming in contact with themetal in the crucible and thereby prevent oxidation and serious loss ofmetal. In furnaces of this character it has heretofore been the practiceto leave a space between the cover and the top of the crucible and toprovide an opening in the center of the cover through which the productsof combustion may escape. The result has been invariably that instead ofmerely passing the top of the crucible and out through the central holein the cover, the flame would curve over the top of the crucible anddownward into the crucible and into contact with the molten metaltherein and would then rise in a central current and pass out throughthe central hole in the cover. This direct contact of the flame with themolten metal has caused appreciable loss of the metal through oxidation.The loss has been so great in fact as to constitute an important item inthe cost of refining all metals and in the refining of the preciousmetals the loss has been serious.

My present invention wholly obviates this loss of metal by oxidationwithout in any way interfering with the melting of the metal. This Iaccomplish by providing a cover for the furnace which will also serve asa cover for the crucible and prevent the entrance of flame into thecrucible and shall be provided with escape holes for the products ofcombustion which will cause the flame to come in contact with the sidesof the crucible clear to the top of the crucible and then pass outwithout coming into contact with the metal.

In the accompanying drawing forming a part of this specification, inwhich reference characters are used to indicate the several parts,Figure1 is a plan view illustrating the preferred form of my novel cover; Fig.2 a section on the line 22 in Fig. 1 looking in the direction of thearrows showing the cover in place on a furnace and a crucible within thefurnace and resting upon a suitable base; Fig. 3 an inverted plan viewof the central portion of the cover; Fig. 4- a plan View correspondingwith Fig. 1, illustrating a modified form of the cover; Fig. 5 a sectionon the line 5-5 in Fig. 4 and corresponding with Fig. 2; and Fig. 6 is asection of a cover slightly modified from the form illustrated in Fig.5.

10 denotes a crucible furnace which may be of any ordinary or preferredconstruction and 11 the combustion chamber, the

portion of said chamber between the crucible and the wall of the furnacebeing usually called the flame-gap. I have not illustrated a burner forthe reason that it is wholly immaterial so far as my present inventionis concerned what type of burner is used. In practice a hydrocarbonburner is ordinarily used which is located in a chamber outside thefurnace and the flame enters the combustion chamber 11 of the furnacethrough a suitable aperture (not shown) near the bottom of said chamber.This opening in practice is preferably placed obliquely to a radial lineso that the flame will swirl around the crucible subjecting all portionsof the outer surface thereof to the direct action of the flame.

12 denotes a crucible ordinarily made of graphite which rests upon abase 13 also ordinarily made of graphite.

14 denotes my novel cover which may be made of any suitable material asmetal, brick, fire clay or graphite and may or may not be hinged to thefurnace as preferred. The cover is of course left unfastened so that itmay be lifted by the gases evolved if sufliciently powerful and thusprevent danger to the furnace. The essential features of the cover arethat it is provided with a central portion adapted to be engagedentirely around by the top of the crucible, thereby preventing theentrance of flame into the crucible and that it is provided with escapeholes in alinement with the flame-gap surrounding the crucible.

In Figs. 1 to 5, inclusive, the cover is shown as provided on itsunderside with a circular table 15 of approximately the diameter of thetop of the crucible with which the top of the crucible engages, asclearly shown in Figs. 2 and 3.

.rality of passages 16 outside of the table,

which converge and lead into a central opening or escape hole 17 in thetop of the cover.

In use the action of my novel cover is as follows: The flame Will swirlaround the crucible coming in contact With every portion of the outersurface thereof clear to the top and Will pass the edge of the table andout through the passages and escape hole, there being no preventableloss of the heating efiect of the flame, and this being accomplishedWithout any contact of the flame With the metal and the consequentoxidation and loss of metal.

The form illustrated in Fig. 5 differs only in that instead ofconverging passages leading into a central opening and out, I provide aplurality of passages 18 outside the table and in direct alinement Withthe flamegap Which pass directly through the cover so that the flame iscaused to come in contact With the entire outer surface of the crucibleclear to the top the same as before. 20 denotes a central hole in thecover Which may or may not be provided as preferred and Which is closedby a plug 21.

The form illustrated in Fig. 6 differs from the form in Fig. 5 in thatinstead of a table to be engaged by the top of the crucible, I provide acentral recess 19 in the underside of the cover which just receives thetop of the crucible.

Having thus described my invention, I claim 1. A cover for cruciblefurnaces having a central imperforate table adapted to be engaged by thetop of a crucible whereby the crucible is closed to the products ofcombustion, said cover having a plurality of passages therethroughoutside of said table and disposed around the same to permit the escapeof the products of combustion.

2.'A cover for crucible furnaces having a. central imperforate tableadapted to be engaged by the top of a crucible whereby the crucible isclosed to the products of combustion and passages outside said table andWithin the cover Which converge and lead into a central opening "for theescape of the products of combustion.

In testimony whereof I affix my signature in presence of two Witnesses.

J ULIANL. R. BROWN. Witnesses:

A. M. VVOOSTER, V S. W. ATHERTON. V

